Core-Shell Nanowires of 3D Topological Insulators

Topological insulators (TI) are promising candidates for next generation electronic/spintronic devices. The gapless surface states (SS) in TI exhibit a very high mobility and strongly suppressed backscattering due to spin-momentum locking. However, to exploit those advantageous one has to decrease the finite bulk conductance present in most TI systems.
One approach to achieve this reduction is to utilize band bending which occurs at the interface between two materials with different Fermi levels. The band bending leads to a charge depletion/ or accumulation near the interface. It therefore provides a tool to shift the fermi energy closer to the Dirac point.
In this work, we have grown core-shell NW using Vapor-Liquid-Solid (VLS) growth and Atomic Layer Deposition (ALD). As core material Bi2Se3 and as shell materials Al2O2 and Sb2Te3 were employed. The uniformity, crystallinity and composition of those core-shell NW was investigated using transmission electron microscopy, nanodiffraction and EDX. Furthermore, devices for transport experiments were built using optical lithography and lift-off techniques. With those devices magneto transport measurements have been performed revealing quantum interference effects such as weak-antilocalization and universal conductance fluctuations.